IPAC2014 - List of Authors (Chen, J.E.)

Paper	Title	Page
TUPME052	Enhanced Laser Ion Acceleration based on Near-Critical Density Plasma Lens	1483
SUSPSNE023	use link to see paper's listing under its alternate paper code
	Y.X. Geng, J.E. Chen, L.R.F. Li, Y.H. Li, Q. Liao, C. Lin, L.H.Y. Lu, Y.R. Lu, H. Wang, X.Q. Yan, Z.X. Yuan, S. Zhao, W.B. Zhao, Y.Y. Zhao, K. Zhu, B.Y. Zou PKU, Beijing, People's Republic of China
	The laser prepulse has large effect on ion acceleration driven by high power laser pulse. Recently, simulations show that with proper prepulse parameters, a near critical density pre-plasma can be generated in the front target. When the main laser pulse propagating in this pre-plasma, it can experience transverse Self-focusing, longitudinal profile steepening and prepluse cleaning at the same time, meaning its quality is spontaneously improved by this “plasma lens”.The effects can greatly improve the energy coupling efficiency of laser pulse into accelerated ions. A 3mJ Ti-Sapphire laser system has been built at PKU in order to experimentally study the pre-pulse effect on a solid target. Fluid simulation show that, after hundreds of picoseconds radiated with this laser pulse, the pre-plasma in front of the target will expand to near critical density with tens of micron scale length, which is suitable as a plasma lens to improve the ion acceleration. A laser interferometer system is built to measure the scale length and density evolution of plasma and the optimum condition of the pre-plasma has been searched using both Aluminum target and home-made DLC target. H.Y.Wang et al, Laser shaping of a relativistic intense, short Gaussian pulse by a plasma lens, PRL, 107,265002, 2011
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TUPME053	Study of the Energy Modulated Electron Cyclotron Resonance Ion Source for the Coupled RFQ-SFRFQ Cavity	1486
	W.L. Xia, J.E. Chen, S.L. Gao, Z.Y. Guo, Y.R. Lu, S.X. Peng, Z. Wang, X.Q. Yan, J. Zhao, K. Zhu PKU, Beijing, People's Republic of China
	The coupled RFQ and SFRFQ cavity has been manufactured and tested recently. According to the beam dynamic design, the input He⁺ beam within 120° phase width is designed for the cavity to achieve over 98% transmission efficiency. An energy modulated electron cyclotron resonance (ECR) ion source was proposed and simulated. To achieve the 1% energy modulation on the 30keV direct current (DC) beam, two simplified RF power feeding structures for beam bunching were studied. The simulations show positive results as well as the bunched beam is achieved by the energy modulated ECR ion source.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME053
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THPME022	Recent Progress of the SSC-LINAC RFQ	3265
	G. Liu, J.E. Chen, S.L. Gao, Y.R. Lu, Z. Wang, X.Q. Yan, K. Zhu PKU, Beijing, People's Republic of China H. Du, Y. He, P. Jiang, X.N. Li, Z.S. Li, J.X. Wu, J.W. Xia, Y.Q. Yang, X. Yin, Y.J. Yuan, X.H. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	Funding: NFSC(11079001) The project of SSC-LINAC RFQ has important progresses in the past year. The machine has been moved to the Institute of Modern Physics in the first season of 2013. The cavity measurement including tests of RF performance and field distribution is carried out again in the laboratory. The Q0 is 6440, and the unflatness of the electric field in longitudinal is ±2.5%. The results demonstrated a good agreement with simulation. The RF and beam commissioning of the RFQ has been carried out in the first half of 2014. The duty factor rose from 5% to CW gradually. By now, the cavity has been operated with 35 kW on CW mode. The measurement of the bremsstrahlung spectrum reveals that the 35 kW power is needed to generate the 70 kV inter-vane voltage. The beam transmission efficiency and energy spread has been obtained in beam commissioning by accelerating 16O⁵⁺ and 40Ar⁸⁺ beams. The efficiency of 40Ar⁸⁺ is as high as 94%, and the output energy is 142.78 keV/u. All the processes and results of the experiments will be discussed in details.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME022
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THPME026	The R&D Status of SSC-LINAC	3277
	X. Yin, H. Du, Y. He, P. Jiang, X.N. Li, L.Z. Ma, J. Meng, L.T. Sun, H. Wang, J.W. Xia, Z. Xu, Y.Q. Yang, Q.G. Yao, Y.J. Yuan, X.H. Zhang, X.Z. Zhang, H.W. Zhao, Z.Z. Zhou IMP, Lanzhou, People's Republic of China J.E. Chen, S.L. Gao, G. Liu, Y.R. Lu, X.Q. Yan, K. Zhu PKU, Beijing, People's Republic of China
	A powerful heavy ion injector SSC-linac is under constructing at IMP in Lanzhou. The continuous wave (CW) 4-rod RFQ operating at 53.667 MHz has been developed as the low beam energy injector linac. The 40Ar⁸⁺ ion beam extracted from the ECR ion source was used for the RFQ commissioning. The particle energy 142.8 keV/u and the 198 euA beam current were measured at the exit of RFQ with the 94% transmission. In this paper, the recent R&D progress of the SSC-LINAC including the development of key components and the beam commissioning results are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME026
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THPME118	A Freon-filled Bubble Chamber for Gamma-ray Detection in Strong Laser-plasma Interaction	3512
	W.B. Zhao, J.E. Chen, C. Lin, L.H.Y. Lu, X.Q. Yan, Y.Y. Zhao, B.Y. Zou PKU, Beijing, People's Republic of China
	When a laser pulse with focused intensity exceeding 1018W/cm² interacts with a solid target, electrons in the focal spot are accelerated to relativistic velocity and where they generate inner-shell vacancies and hard x-ray(>10 keV) spectral line and Bremsstrahlung radiation. In laser plasma interactions, the resonance between betatron motion of electrons and ultraintense laser pulses is an interesting phenomenon in both electron acceleration and gamma photon production. Even though the gamma-ray synchrotron is micron scale, the energy ranges from ~1 MeV to ~102MeV. To detect the energy of the gamma-ray accurately is particularly significant. Owing to a lot of various energy of gamma-ray are emitted in femtosecond scale, which are impossible distinguished from each other on the time. A small freon-filled bubble chamber is being built to measure the energy spectrum of high-energy photons. After that, we can calculate the electron’s energy and then offer the data for various of electron acceleration theories. It combines a good spatial resolution with a large depth of field, allowing a large number of tracks. This improves the statistical quality of the photon spectrum.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME118
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Paper

Title

Page

TUPME052

Enhanced Laser Ion Acceleration based on Near-Critical Density Plasma Lens

1483

SUSPSNE023

use link to see paper's listing under its alternate paper code

Y.X. Geng, J.E. Chen, L.R.F. Li, Y.H. Li, Q. Liao, C. Lin, L.H.Y. Lu, Y.R. Lu, H. Wang, X.Q. Yan, Z.X. Yuan, S. Zhao, W.B. Zhao, Y.Y. Zhao, K. Zhu, B.Y. Zou
PKU, Beijing, People's Republic of China

The laser prepulse has large effect on ion acceleration driven by high power laser pulse. Recently, simulations show that with proper prepulse parameters, a near critical density pre-plasma can be generated in the front target. When the main laser pulse propagating in this pre-plasma, it can experience transverse Self-focusing, longitudinal profile steepening and prepluse cleaning at the same time, meaning its quality is spontaneously improved by this “plasma lens”.The effects can greatly improve the energy coupling efficiency of laser pulse into accelerated ions. A 3mJ Ti-Sapphire laser system has been built at PKU in order to experimentally study the pre-pulse effect on a solid target. Fluid simulation show that, after hundreds of picoseconds radiated with this laser pulse, the pre-plasma in front of the target will expand to near critical density with tens of micron scale length, which is suitable as a plasma lens to improve the ion acceleration. A laser interferometer system is built to measure the scale length and density evolution of plasma and the optimum condition of the pre-plasma has been searched using both Aluminum target and home-made DLC target.
H.Y.Wang et al, Laser shaping of a relativistic intense, short Gaussian pulse by a plasma lens, PRL, 107,265002, 2011

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME052

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPME053

Study of the Energy Modulated Electron Cyclotron Resonance Ion Source for the Coupled RFQ-SFRFQ Cavity

1486

W.L. Xia, J.E. Chen, S.L. Gao, Z.Y. Guo, Y.R. Lu, S.X. Peng, Z. Wang, X.Q. Yan, J. Zhao, K. Zhu
PKU, Beijing, People's Republic of China

The coupled RFQ and SFRFQ cavity has been manufactured and tested recently. According to the beam dynamic design, the input He⁺ beam within 120° phase width is designed for the cavity to achieve over 98% transmission efficiency. An energy modulated electron cyclotron resonance (ECR) ion source was proposed and simulated. To achieve the 1% energy modulation on the 30keV direct current (DC) beam, two simplified RF power feeding structures for beam bunching were studied. The simulations show positive results as well as the bunched beam is achieved by the energy modulated ECR ion source.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME053

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPME022

Recent Progress of the SSC-LINAC RFQ

3265

G. Liu, J.E. Chen, S.L. Gao, Y.R. Lu, Z. Wang, X.Q. Yan, K. Zhu
PKU, Beijing, People's Republic of China
H. Du, Y. He, P. Jiang, X.N. Li, Z.S. Li, J.X. Wu, J.W. Xia, Y.Q. Yang, X. Yin, Y.J. Yuan, X.H. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

Funding: NFSC(11079001)
The project of SSC-LINAC RFQ has important progresses in the past year. The machine has been moved to the Institute of Modern Physics in the first season of 2013. The cavity measurement including tests of RF performance and field distribution is carried out again in the laboratory. The Q0 is 6440, and the unflatness of the electric field in longitudinal is ±2.5%. The results demonstrated a good agreement with simulation. The RF and beam commissioning of the RFQ has been carried out in the first half of 2014. The duty factor rose from 5% to CW gradually. By now, the cavity has been operated with 35 kW on CW mode. The measurement of the bremsstrahlung spectrum reveals that the 35 kW power is needed to generate the 70 kV inter-vane voltage. The beam transmission efficiency and energy spread has been obtained in beam commissioning by accelerating 16O⁵⁺ and 40Ar⁸⁺ beams. The efficiency of 40Ar⁸⁺ is as high as 94%, and the output energy is 142.78 keV/u. All the processes and results of the experiments will be discussed in details.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME022

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPME026

The R&D Status of SSC-LINAC

3277

X. Yin, H. Du, Y. He, P. Jiang, X.N. Li, L.Z. Ma, J. Meng, L.T. Sun, H. Wang, J.W. Xia, Z. Xu, Y.Q. Yang, Q.G. Yao, Y.J. Yuan, X.H. Zhang, X.Z. Zhang, H.W. Zhao, Z.Z. Zhou
IMP, Lanzhou, People's Republic of China
J.E. Chen, S.L. Gao, G. Liu, Y.R. Lu, X.Q. Yan, K. Zhu
PKU, Beijing, People's Republic of China

A powerful heavy ion injector SSC-linac is under constructing at IMP in Lanzhou. The continuous wave (CW) 4-rod RFQ operating at 53.667 MHz has been developed as the low beam energy injector linac. The 40Ar⁸⁺ ion beam extracted from the ECR ion source was used for the RFQ commissioning. The particle energy 142.8 keV/u and the 198 euA beam current were measured at the exit of RFQ with the 94% transmission. In this paper, the recent R&D progress of the SSC-LINAC including the development of key components and the beam commissioning results are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME026

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPME118

A Freon-filled Bubble Chamber for Gamma-ray Detection in Strong Laser-plasma Interaction

3512

W.B. Zhao, J.E. Chen, C. Lin, L.H.Y. Lu, X.Q. Yan, Y.Y. Zhao, B.Y. Zou
PKU, Beijing, People's Republic of China

When a laser pulse with focused intensity exceeding 1018W/cm² interacts with a solid target, electrons in the focal spot are accelerated to relativistic velocity and where they generate inner-shell vacancies and hard x-ray(>10 keV) spectral line and Bremsstrahlung radiation. In laser plasma interactions, the resonance between betatron motion of electrons and ultraintense laser pulses is an interesting phenomenon in both electron acceleration and gamma photon production. Even though the gamma-ray synchrotron is micron scale, the energy ranges from ~1 MeV to ~102MeV. To detect the energy of the gamma-ray accurately is particularly significant. Owing to a lot of various energy of gamma-ray are emitted in femtosecond scale, which are impossible distinguished from each other on the time. A small freon-filled bubble chamber is being built to measure the energy spectrum of high-energy photons. After that, we can calculate the electron’s energy and then offer the data for various of electron acceleration theories. It combines a good spatial resolution with a large depth of field, allowing a large number of tracks. This improves the statistical quality of the photon spectrum.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME118

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)